. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. 50 THE SPRING GRAIN-APHIS OR " GREEN ; zero, with no protection, is fatal to Toxoptera, except to the egg, but the fact that it withstood the winter in 1890 can easily be accounted for. That winter was unusually mild throughout, with the excep- tion of the dates mentioned, and if one consults the weather records it. Fig. 9.—The spring grain-aphis: Oviparous female, showing eggs within the abdomen. actual size, mm. (Original.) Enlarged; will be found that on January 24 there were inches of s
. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. 50 THE SPRING GRAIN-APHIS OR " GREEN ; zero, with no protection, is fatal to Toxoptera, except to the egg, but the fact that it withstood the winter in 1890 can easily be accounted for. That winter was unusually mild throughout, with the excep- tion of the dates mentioned, and if one consults the weather records it. Fig. 9.—The spring grain-aphis: Oviparous female, showing eggs within the abdomen. actual size, mm. (Original.) Enlarged; will be found that on January 24 there were inches of snow, Feb- ruary 9, inches, and March 6, 4 inches. The covering of snow in each instance would appear to have been sufficient to protect the Toxoptera, as on December 8, 9, and 10, 1909, at Lafayette, Ind., the temperature fell as low as from — 1° F. to —4° F. below zero, and plant-lice of all kinds, in ^ the rearing cages out of doors, were killed, while those in a near-by wheat field, covered with several inches of snow, were found to be in good condition on December 13, at which time the cold spell was broken and the ground began to thaw. As a rule, Toxoptera breeds slowly in October and November, at which time the majority become oviparous females (figs. 9, 10) and males (fig. 6).. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States. Bureau of Entomology. Washington : G. P. O.
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